This invention relates generally to a trigger actuated pump sprayer to be mounted via a closure cap to the top of a container of liquid to be sprayed upon manual actuation of a trigger lever. The trigger sprayer typically has an inlet check valve for inletting product into the pump chamber during each suction stroke of the pump piston. An outlet or discharge check valve is likewise provided for valving the discharge orifice closed during each suction stroke and for valving the pressurized product through the discharge during each pump pressure stroke. The inlet valve is located at some suitable location upstream of a port leading into the pump chamber, and the discharge valve is located downstream of the pump chamber port at a location which may be adjacent the pump chamber or at the nozzle end of the sprayer. Rather than separate ports the pump chamber may have a single port with the intake and discharge valves respectively located upstream and downstream thereof.
The intake valve is very often in the form of an inlet ball check valve while the separate and oftentimes distanced discharge valve is in the form of an elastomeric flap valve or an annular valve.
U.S. Pat. No. 4,527,741 discloses a trigger sprayer having an inlet ball check valve and a separate discharge valve in the form of either another ball check valve or an umbrella-like valve, the intake and discharge valve units being located in a passageway extending from the intake passage and communicating with the ported pump chamber. A dip tube retainer is required for supporting both intake and discharge valves and for maintaining them in a relationship which straddles the ported pump chamber.
Moreover, the piston return spring provided for the trigger sprayer may be external to the pump chamber to avoid any non-compatibility problems between the liquid to be sprayed and a metallic spring located within the pump chamber. External piston return metal spring arrangements are known, as well as external piston return plastic spring assemblies. An example of the latter assembly is disclosed in U.S. Pat. No. 5,228,602 in which a separate piston return spring having a flat surface with one end positioned adjacent the back wall of the trigger and its other end positioned rearwardly of the trigger and engaging against the pump body.
The need arises to provide low cost triggers for a variety of applications which by popular demand are increasing. In order to minimize production and assembly costs, the number of parts of the trigger sprayer assembly must be reduced while retaining the basic functions of the pump sprayer. Cost savings relating to elimination of a part or parts of the assembly can, in terms of production and assembly operations, amount to measurable savings in price to the customer.